I. Field of the Invention
The present invention relates to a method for simulating the gauging of a liquid tank, in particular a liquid fuel tank of a vehicle, preferably by means of a data processing device containing a virtual model of the tank comprising an internal volume, a wall that defines said internal volume, and a liquid extraction point in this internal volume.
The expression “liquid tank” is understood to mean any tank for a liquid material of any nature. The invention preferably applies to those that are mounted on motorized vehicles such as motor vehicles, such as fuel tanks or tanks for pollution-control additives (for example, urea, which is used to reduce the NOx in the exhaust gases). It applies more particularly to liquid fuel tanks.
Such tanks may be manufactured by any known technique before being equipped with a liquid gauge. They may, for example, be obtained by pressing and/or welding steel sheets, by extrusion-blow moulding of parisons made of plastic of various types, by pouring or injecting various materials into a mould or by any other technique suitable for the manufacture of closed hollow objects capable of containing liquids. The invention is particularly suitable for the simulation of plastic tanks, more particularly those obtained by the extrusion-blow moulding technique.
The term “gauge” is understood to mean any gauge for measuring the volume of liquid, based on the observation of the level of the free surface of the liquid contained in a tank such as a float gauge, a gauge based on measuring the variation of an electrical property of the gauge immersed in the liquid or a gauge that combines a float system and an electrical device that is coupled thereto, or any other type of gauge. The gauge conforming to the invention may be in various forms such as a rectilinear gauge, circular gauge, or gauge of any shape.
The terms “gauging curve” intend to designate the set of measurement points for the liquid level inside the hollow body. According to the invention, the real gauging curve is established based on a simulated (calculated) curve which approached the ideal gauging curve as will be explained below.
The term “vehicle” is understood to mean any mobile machine that can be moved in any direction that varies in the course of the movement along a slope that may itself also vary with the movement and more particularly those that can be moved over a horizontal or sloped surface.
The expression “data processing device” is understood to mean any programmable device that makes it possible to process a data set, in particular in the form of computer data files, according to a set of logic instructions, or software. In particular, it is understood to mean, in this way, any programmable electronic computer.
The expression “electronic medium” is understood to mean any data storage device that can be read by such a data processing device such as, for example, an optical memory device such as a CD-Rom, DVD, or others, a magnetic memory device such as a hard disk, magnetic tape, floppy disk, or others, or an electronic memory device such as a memory chip, flash memory or others.
The expression “virtual model” is understood to mean any detailed description in the form of computer data files, in particular computer data files capable of being processed by computer-aided design (CAD) software.
II. Description of Related Art
In the production of liquid tanks, one of the greatest obstacles is that of ensuring the gauging accuracy. This problem is particularly acute in the field of liquid fuel tanks for vehicles, since the design constraints and especially space constraints for these tanks often impose very complex shapes and present particular gauging problems. Moreover, in use, such tanks are often subjected to inclinations and/or accelerations that cause inclinations of the liquid surfaces and thus errors in gauging may be considerable if the location, shape and orientation of the liquid gauge are not optimal.
For a long time, the parameters for the location, shape and orientation of gauges were determined by trying several different configurations until a configuration meeting predetermined specifications was found. However this is a relatively ineffective method, requiring considerable means and subject to error. In order to facilitate the configuration of the gauges, an iterative simulation method was therefore proposed in European Patent EP 0 595 389, making it possible to design more accurate gauges, in particular with CAD means.
However, this prior art method also comprises drawbacks. In particular, the iterative nature of the method requires a considerable computation time.